package com.health.core.util;

import lombok.SneakyThrows;
import org.apache.commons.codec.binary.Base64;
import org.springframework.util.AlternativeJdkIdGenerator;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

public class GeneralUtil {

    /**
     * 高效能生成UUID
     * @return
     */
    public static String getUUID() {
        AlternativeJdkIdGenerator alternativeJdkIdGenerator = new AlternativeJdkIdGenerator();
        return alternativeJdkIdGenerator.generateId().toString().replace("-", "");
    }

    private static final String KEY_ALGORITHM = "AES";

    private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";

    /**
     * AES加密
     * @param passwd  加密的密钥
     * @param content 需要加密的字符串
     * @return 返回Base64转码后的加密数据
     * @throws Exception
     */
    @SneakyThrows
    public static String encrypt(String passwd, String content) {
        // 创建密码器
        Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);

        byte[] byteContent = content.getBytes("utf-8");

        // 初始化为加密模式的密码器
        cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(passwd));

        // 加密
        byte[] result = cipher.doFinal(byteContent);

        //通过Base64转码返回
        return Base64.encodeBase64String(result);
    }

    /**
     * AES解密
     * @param passwd    加密的密钥
     * @param encrypted 已加密的密文
     * @return 返回解密后的数据
     * @throws Exception
     */
    public static String decrypt(String passwd, String encrypted) {
     try {
         //实例化
         Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);

         //使用密钥初始化，设置为解密模式
         cipher.init(Cipher.DECRYPT_MODE, getSecretKey(passwd));

         //执行操作
         byte[] result = cipher.doFinal(Base64.decodeBase64(encrypted));

         return new String(result, "utf-8");
     }catch (Exception e){
         e.printStackTrace();
         return "";
     }
    }

    /**
     * 生成加密秘钥
     * @return
     */
    private static SecretKeySpec getSecretKey(final String password) throws NoSuchAlgorithmException {
        //返回生成指定算法密钥生成器的 KeyGenerator 对象
        KeyGenerator kg = KeyGenerator.getInstance(KEY_ALGORITHM);
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
        random.setSeed(password.getBytes());
        //AES 要求密钥长度为 128
        kg.init(128, random);

        //生成一个密钥
        SecretKey secretKey = kg.generateKey();
        // 转换为AES专用密钥
        return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);
    }

}







